Plural expansion refrigeration system



April 28, 1953 H. T. CHAPPELLE PLURAL EXPANSION REFRIGERATION SYSTEMFIG. 3

Filed Sept. lfl, 1949 INVENTOR. H. T. CHAPPELLE ilVilllill AT TORNEYPatented Apr. 28, 195 3 UNITED STATES PATENT OFFICE PLURAL EXPANSIONREFRIGERATION SYSTEM This invention relates to refrigeration and moreparticularly to an improved system including a novel evaporator or heatabsorbing means by the use of which improved efificiency may beobtained.

It is an object of the present invention to provide a refrigerationsystem having improved operating characteristics in which the evaporatoris of novel construction by means of which improved efilciency may beobtained.

A further object of the invention is to provide an improvedrefrigeration system employing novel operating characteristics andimproved evaporator construction in which a refrigerant i used which isparticularly designed for use with the system embodying the presentinvention.

These and other objects of the invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings, wherein:

Fig. 1 is a diagrammatic layout of one embodiment of the invention;

Fig. 2, a section on the line 2-2 of Fig. 1; and

Fig. 3, a section on the line 3-3 of Fig. 2.

Referring to the drawings the system includes a compressor ID fordelivering compressed refrigerant into a discharge line II to bereceived in a condenser I2. From the condenser the liquid refrigerantpasses through line I3 into a receiver l4. From the receiver therefrigerant passes through line l5 having a control valve [6 to anexpansion valve I! just before entry into an evaporator 18. From theevaporator a suction line 32 leads back to the compressor 10.

The evaporator consists of a plurality of pairs of tubes I9, 20, I9, 20,etc., two pairs being shown for convenience. It is understood, however,that the invention contemplates the use of a multiplicity of pairsdepending upon the capacity of the particular unit. The tubes areconnected in series so that the refrigerant fiows through each of thetubes individually.

From the expansion valve I! the refrigerant flows into the tube l9,through the tube, and out itsopposite end into the elbow 22 which feedsinto a header tube 23. The header tube is disposed transversely of andadjacent the ends of the next pair of tubes I9, 20. From the other endof the header tube an elbow 24 is connected substantially axiallyof thetube ,20 to a small orifice nozzle 25 positioned within the tube 20.Therefrig'erant then flow through nozzle 25 into the tube 20 and at itsfar end out through a tube p 26 and into the tube [9' through a smallorifice nozzle 21 positioned axially of the tube.

At the opposite end of the tube IS the refrigerant is discharged throughthe elbow 28 into a header 28 from whence it passes through an elbow 38into the tube 20 by means of a small orifice nozzle 3|. At the far endof the tube 20 the refrigerant is discharged into the suction line 32 tothe compressor.

The ends of the tubes are provided with jackets 35 and 3B which extendfor a small distance from each end of the tube and include theconnections at the ends of the tubes. The joints between the jackets andthe tubes and the connections are sealed in order that the jackets maybe evacuated. Suitable insulation may be provided, if desired,

to reduce the transfer of heat from the jacket to the tubes byconduction. For the purposes of evacuation of the jacket, lines 3! and38 are connected to the jackets 35 and 36 respectively and are joined ata T 39 to a connection 40 provided with a check valve 4| which is placedin the suction line 32. It will be apparent that during the operation ofthe compressor the jackets 35 and 36 will be under a vacuumcorresponding approximately to the suction pressure of the compressor.

Although other refrigerants may be employed, a mixture consisting ofcarbon tetrachloride, anhydrous methylalcohol, and ethylene dichloridein the proportion of 20, 60, and 20 by volume respectively is preferred.This mixture is resistant to fire and has a boiling point ofapproximately 117 F. at atmospheric pressure.

In the operation of the device, the compressor discharges compressedrefrigerant to the condenser at a relatively low pressure, which may beon the order of about zero gage. From the condenser the liquidrefrigerant drains to the receiver and thence through the line It to theexpansion valve ll. After passing through the expansion valve therefrigerant goes into the tube 20.

In passing through the expansion valve the pressure is reduced to about12 Hg vacuum under normal operating conditions, the refrigerant beingpartially gasified in going through the tube 19. At the end of the tubethe mixture of gas and liquid refrigerant passes out of the tube throughthe elbow 22.

The ends of the tubes i9, 26, i9 and 20, etc, the elbow connections andthe header tubes 23 and 24 are confined within the jacket 36.

As the mixture of liquid and'gaseous refrigerant passes from the endofthe tube through the elbow 22 it drains into the header 23 whichcollects the mixture prior to its passage into the next tube. The headermay be disposed adjacent or in contact with the next pair of tubes, and

subjected to the temperature prevailing in those tubes. Inasmuch as therefrigerant entering each tube passes through a pressure-reducingnozzle, it follows that correspondingly lower temperatures are attainedin the succeeding cylinders comprising the evaporator. It is apparenttherefore that heat exchange may take place under these circumstancesbetween the refrigerant passing through a given header and that in thenext succeeding pair of cylinders.

From the header the mixture fiows upwardly into the elbow 24 and intothe nozzle 25 where it is expanded into the tube 26. As a result of theexpansion the mixture undergoes a drop in pressure and passes throughthe tube 28 absorbing heat as it goes.

The refrigerant then passes through the remaining tubes and theirnozzles and out of the last tube 2d into the suction line 32. In orderthat the system operate efiiciently the suction in the line 32 should beon the order of approximately 19 Hg vacuum but this may be varied toconform to the characteristics or the particular refrigerant employed.

By reason of the novel construction and arrangement of the evaporator,including the tubes having their ends confined in the jacket undervacuum, the arrangement of the headers, the refrigerant employed, andthe order of vacuum under which the system operates, an improvedefiiciency is attained so that a greater output per unit of input isobtainable than with conventional systems. Furthermore, the jackets areprovided With efiective insulation at low cost due to the utilization ofthe compressor for the production of the vacuum therein.

It will be obvious to those skilled in the art that various changes maybe made in the invention without departing from the spirit and scopethereof and therefore the invention is not limited by that which isshown in the drawings and described in the specification but only asindicated in the appended claims.

What is claimed is:

1. An evaporator for a refrigeration system comprising a plurality ofpairs of elongated cy1- inders including a last pair, one end of eachcylinder providing an intake and the other end a discharge for theparticular cylinder, the discharge end of the first cylinder of eachpair except said last pair being connected to a cylindrical headerdisposed transversely of and adjacent the ends of the next pair ofcylinders, a connection extending from the header to a nozzle disposedsubstantially axially of and extending into the intake end of the secondcylinder of the pair, a connection from the discharge end of the secondcylinder of the pair to a nozzle extending into the intake end of thefirst cylinder of the next pair, the connection from the discharge endof the second cylinder of the last pair being provided for connection toa compressor suction line, and a connection from the discharge end ofthe first cylinder of the last pair to a nozzle disposed substantiallyaxially of and extending into the intake end of the second cylinder ofthe pair.

2. In a refrigeration system, a compressor having a suction line, anevaporator comprising a plurality of pairs of elongated cylindersconnected in series, a first cylinder of each pair being connected bymeans of an elbow extending from the lower portion of its discharge endto a cylindrical header disposed transversely of and adjacent theextremities of the cylinders, an elbow extending from the header to anozzle disposed substantially axially of and extending into the secondcylinder in the pair, connections being provided to connect the secondcylinder of a pair to the first cylinder of the next pair, a jackethousing the ends of the connections at the ends of the cylinders, andmeans for evacuating substantially all of the air from the jackets inorder to produce a substantial vacuum therein.

3. In a refrigeration system, a compressor having a suction line, anevaporator comprising a plurality of pairs of elongated cylindersconnected in series, a first cylinder of each pair being connected to acylindrical header disposed transversely of and adjacent the extremitiesof the cylinders, means connecting the header to a nozzle extending intothe second cylinder in the pair, connections being provided to connectthe second cylinder of a pair to the first cylinder of the next pair, a,jacket housing the ends of the connections at the ends or the cylinders,and means for evacuating substantially all of the air from the jacketsin order to produce a substantial vacuum therein.

a. The structure of claim 3, the last means comprising connections tothe suction line of the compressor.

5. A low pressure refrigeration system comprising pump means capable ofproducing a high order of vacuum; a condenser connected to the pumpmeans; a receiver connected to the condenser; an expansion valveconnected to the receiver; an evaporator connected to the expansionvalve, the evaporator comprising a plurality of pairs of elongatedcylindrical tubes arranged in parallel, connections at the ends of thetubes providing for series flow through the tubes, the connections for apreceding pair being in proximity to a succeeding pair,-pressurereducing means being provided for each tube; and a sealed jacket housingthe ends of the evaporator tubes and their connections, the jacketshaving lines'extending to the pump means whereby the jackets may beevacuated.

6. In a refrigeration system having compressor means, the compressormeans having suction means, an evaporator comprising a plurality ofelongated cylindrical tubes connected in series for the passage ofrefrigerant, each tube having intake means, expansion means in theintake means of each tube for causing a pressuredrop in the refrigerantas it enters each of the tubes, sealed jacket means housing the ends ofthe tubes, and means connecting said jacket means to the suction meansfor maintaining the jacket means under evacuation by the compressor.

HOMER T. CHAPPELLE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,039,796 Hiller May 5,1935 2,081,883 Philipp May 25, 19372,137,373 Williams Nov. 22, 1933 2,428,386 I-lubaclrer l July'l, 1947

